As a popular psychostimulant, methamphetamine (METH) use leads to long-lasting, strong euphoric effects. While METH abuse is common in the general population, approximately 10-15% of human immunodeficiency virus-1 (HIV-1) patients report METH abuse. METH exacerbates the severity and onset of HIV-associated neurocognitive disorders (HAND). Both METH and HAND neuropathogenesis mechanistically concur with neuroinflammation, astrocyte activation, brain hyperthermia, oxidative stress and excitotoxicity. Thus, METH affects a multitude of astrocyte functions, yet the mechanism through which this is attained is unclear. Recently, we reported trace amine associated receptor 1 (TAAR1) as a novel astrocyte receptor for METH signaling. In this proposal, we will investigate METH-mediated regulation and activation of TAAR1 and the downstream effects that lead to exacerbation of HAND in the context of METH comorbidity. Our preliminary data in this proposal suggest a critical role of pCREB in astrocyte-METH signaling. Recently, TAAR1 has also emerged as a promising pharmacotherapeutic target. We propose that METH-abuse in HAND modulates astrocyte-TAAR1 and downstream signaling via cAMP, [Ca2+]i, PKA/ERK, PKC and NF-kB regulating CREB. These pathways play critical mechanistic role(s) in astrocyte-mediated neurotoxic outcomes, including mitochondrial damage, oxidative stress, excitotoxicity and neuroinflammation. Further, we propose astrocyte-TAAR1 as a novel therapeutic target in HAND and METH comorbidity. We will conduct investigations in the molecular regulation of TAAR1 in Aim 1, delineate the complex intracellular signaling pathways altering astrocyte function in Aim 2 and lastly extend the work to potential therapeutic avenues using a HAND relevant animal model in Aim 3. First, we will investigate the regulation of astrocyte-TAAR1 and following cAMP changes leading to gliosis and neuroinflammation (Aim 1: Molecular). Human astrocytes activated with virotoxins, or those expressing viral proteins, with/out METH will be used. TAAR1-GFP overexpression model will be used to identify TAAR1-specific responses. Next, we will delineate astrocyte-TAAR1 intracellular signaling leading to METH comorbidity in HAND (Aim 2: Signaling and function). Lastly, we will evaluate TAAR1 as a potential therapeutic target (Aim 3: Translational). Taken together, we employ a combined cellular and molecular approach with ex vivo, in vitro and in vivo studies that will have broader implication(s) for astrocyte-TAAR1 regulation, its role in substance abuse-based neurological deficits and as a novel therapeutic target for METH comorbidity in HAND.